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我国铁路线纵横交错、密如蛛网,经过不同的地形区,知识多而散。因此,需要对繁杂的知识从不同的角度进行整理归类。一、南北向铁路1.京哈—京广线途经的主要城市有:北京、天津、唐山、秦皇岛、沈阳、长春、哈尔滨、石家庄、郑州、武汉、岳阳、长沙、株洲、广州;经过的地形区有:松嫩平原、辽河平原、华北平原、长江中下游平原、东南丘陵、两广丘陵、珠江三角洲。 相似文献
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INTRODUCTION High data rate and high quality multimedia ser- vices are required in beyond third generation (B3G) and fourth generation (4G) mobile communications. Space-time coding scheme has been proposed (Tarokh et al., 1998; 1999) to achieve higher capacity and data rate. So far, most research on space-time coding assumed that accurate channel estimations are available at the receivers. However, accurate channel estimation is difficult and too many training symbols are required in a r… 相似文献
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